Our planet's protective shell isn't as strong as it once was. Its magnetic strength has dropped dramatically over the last two centuries, and no one knows why.
At the same time, a worrying soft-spot in the field known as the South Atlantic Anomaly has blistered across the Atlantic Ocean, posing a challenge for orbiting satellite circuits.
Both of these alarming facts raise the possibility that we're witnessing the beginnings of a magnetic pole reversal, which would flip the compass points completely upside down.
However, the authors of a new study that simulates the planet's magnetic field in the recent past advise that we shouldn't be too certain that this will happen.
"Based on similarities with the recreated anomalies, we predict that the South Atlantic Anomaly will probably disappear within the next 300 years, and that Earth is not heading towards a polarity reversal," says geologist Andreas Nilsson of Lund University in Sweden, based on parallels with the reconstructed anomalies.
At the very least, not anytime soon. So, for the time being, we may relax.
Still, if our geological past is any indication, our planetary magnetic field's flowing lines will ultimately point in the other direction.
It's unclear what such a shift would imply for mankind. Life on Earth looked to suffer through a tough period the previous time such a big catastrophe happened, only 42,000 years ago, when a downpour of high-speed charged particles smashed through our atmosphere.
It's unclear if we humans noticed, and if so, whether we responded by spending a little more time shielding.
Given today's reliance on electronic equipment, which might be susceptible without the protection of a magnetic umbrella, even the quickest field reversals in the near future would leave us defenseless.
As a result, geologists are interested in determining which wiggles, wobbles, and wanderings in the field signal disaster and which indicate business as usual.
The way the magnetic field's direction drives particles in molten materials to line up before being held in place when they solidify provides a lot of information about the field's history. Digging through layers of mineralized arrows reveals a pretty accurate record of the compass's direction throughout millennia.
Similarly, ceramic objects from ancient sites might capture the field's orientation in clay before fire, providing a glimpse of the field in more recent periods.
Researchers from Lund University and Oregon State University used samples of volcanic rocks, sediments, and artifacts from throughout the world to rebuild a precise chronology of our planet's magnetic shell dating back to the last ice age.
"We have mapped changes in the Earth's magnetic field over the past 9,000 years, and anomalies like the one in the South Atlantic are probably recurring phenomena linked to corresponding variations in the strength of the Earth's magnetic field," Nilsson adds.
With thousands of years of perspective, it's evident that the South Atlantic soft-spot isn't entirely unusual. A comparable geological event occurred in 1600 BCE, lasting around 1,300 years until evening out.
Assuming the same underlying principles are at work, the current weakening patch will quickly regain strength and fade away without requiring global reconfiguration. It's also possible that the magnetic field as a whole will regain its strength, which hasn't been seen since the early 19th century.
This isn't proof that a reversal won't happen soon; it's merely additional data that suggests we shouldn't perceive current anomalies of weakening as strong indicators of a polar flip.
That's excellent news in some ways. However, it leaves us in the dark as to how such a large geological process would unfold during a human lifetime.
Having precise records like this one helps to develop a clearer picture, so maybe we'll be ready if the worst comes.
